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Acta Phytopathologica et Entomologica Hungarica
Authors: A. Kamalakannan, L. Mohan, K. Kavitha, S. Harish, R. Radjacommare, S. Nakkeeran, V. K. Parthiban, R. Karuppiah and T. Angayarkanni

Five isolates of Trichoderma viride, Pseudomonas fluorescens and four isolates of Bacillus subtilis were evaluated for their ability to control Rhizoctonia solani, the causal agent of stem and stolon rot of peppermint (Mentha piperita Lin.). Of the various isolates of T. viride, P. fluorescens and B. subtilis tested, TVUV10, PFMMP and BSG3 showed the maximum inhibition of mycelial growth of R. solani. Among these isolates, P. fluorescens, PFMMP recorded the highest inhibition zone against R. solani in vitro and was very effective in reducing disease incidence in greenhouse condition. The effective isolates were evaluated for their ability to induce defense related enzymes and chemicals in plants. Increased activity of phenylalanine ammonia lyase (PAL), peroxidase (PO), polyphenoloxidase (PPO) and total phenolics were recorded in the biocontrol agents pretreated peppermint plants challenged with R. solani. P. fluorescens isolate PFMMP recorded early and increased synthesis of all defense related enzymes and total phenol. Thus, the present study shows that application of biocontrol agents; induce defense related enzymes involved in phenyl propanoid pathway in addition to direct antagonism which collectively contribute for enhanced resistance against invasion of R. solani in M. piperita.

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/58 461 470 Berghem, L. E. R., & Petterson, L. G. (1974): The mechanism of enzymatic cellulose degradation. Isolation and some properties of a β-glucosidase in T. viride . Eur. J

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The effect of Trichoderma harzianum and Trichoderma viride (isolated from mycoflora in the rhizosphere of onion) in increasing the growth of onion was studied in a completely randomized design in pots with 12 replications under greenhouse conditions at 21°C with a 12-h light/dark cycle (fluorescent and incandescent lighting). The biological control of Sclerotium cepivorum Berk, the causal agent of white rot of onion, was also investigated in this experiment. The addition of Trichoderma spp. to autoclaved soil (inoculation of 2/3 of the top soil in the pots with 4% (v/v) inoculum of T. harzianum and T. viride) significantly increased the growth and fresh weight of the onion plants (P=1%). The biological control of S. cepivorum was achieved with T. harzianum and T. viride, but no significant difference was observed between the two species.

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Acta Phytopathologica et Entomologica Hungarica
Authors: S. Mathiyazhagan, K. Kavitha, G. Chandrasekar, S. Nakkeeran, K. Manian, A. S. Krishnamoorthy, A. Sankaralingam and W. G. D. Fernando

The commercial cultivation of Phyllanthus amarus (Schum and Thonn) has led to the outbreak of stem blight caused by Corynespora cassiicola (Berk and Curt) Wei. Infection of C. cassiicola is reported on P. amarus for the first time. C. cassiicola produced glycoproteinaceous toxin responsible for the symptoms simirlarly produced by the pathogen. B. subtilis (CBE4), P. chlororaphis (PA23), endophytic P. fluorescens (ENPF1)  and T. viride (Tv-MNT7) degraded the toxin of C. cassiicola.

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Cadmium, nickel or zinc contaminated soils originating from a long-term heavy metal field experiment were used to assess the influence of those particular treatments on the coexistence of various Trichoderma species. The abundance of six indigenous Trichoderma spp. - T . atroviride , T . harzianum , T . pubescens , T . tomentosum , T . virens and T . viride - were studied 12 years after the application of Cd, Zn and Ni salts on four levels (0, 30, 90 and 270 mg·kg -1 ) in a calcareous chernozem soil. Trichoderma fungal colonies from the soil particles were estimated on selective media. The isolated strains were taxonomically characterized by microscopic visualization.  A reduced Trichoderma fungal colonization was found at the lower ratio of the studied metals. No colonization could be recorded in the case of Cd, and a slightly increased abundance at Ni and Zn metal salts at the highest 270 mg·kg -1 doses. The species composition of the fungi varied considerably in the contaminated samples as a function of the metals and the applied doses. Correlation analysis revealed that the population density of T . atroviride , T . harzianum , T . pubescens , T . viride was negatively affected by the available Cd concentration. The nickel content of the soil, however, correlated positively with the abundance of T . harzianum (r = 0.955) and T . virens (r = 0.964). In addition to this finding, the frequency of T . viride and T . tomentosum showed significant positive and negative correlation with the Zn treatment (r = 0.955; r = -0.965, respectively). Great differences between the correlation and partial correlation coefficients suggested that the heavy metals may alter not only the abundance of the fungi, but the interspecific relationships among the indigenous Trichoderma population, as well. This fact is considered to have further influence on some other biotic parameters and the soil functioning in heavy-metal-affected soils.

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Acta Biologica Hungarica
Authors: Parisa Rahimi Tamandegani, Doustmorad Zafari, Tamás Marik, András Szekeres, Csaba Vágvölgyi and László Kredics

Five Iranian Trichoderma isolates from species T. viride, T. viridescens, T. asperellum, T. longibrachiatum and T. citrinoviride — selected from the Fungal Collection of the Bu Ali Sina University, Hamedan, Iran — were investigated for their peptaibol production. All examined isolates showed remarkable antibacterial activities during the screening of their extracts for peptaibol content with a Micrococcus luteus test culture. HPLC-ESI-IT MS was used for identification and elucidation of the amino acid sequences of peptaibols. The detected peptaibol compounds contain 20 or 18 amino acid residues and belong to the trichobrachin and trichotoxin groups of peptaibols, respectively. T. longibrachiatum and T. citrinoviride produced trichobrachins, while trichotoxins could be detected in T. viride, T. viridescens and T. asperellum. Out of 37 sequences detetermined, 26 proved to be new, yet undescribed compounds, while others were identified as previously reported trichotoxins (trichotoxin A-50s and T5D2) and trichobrachins (longibrachins AI, AII, AIII, BII and BIII). Compounds within the two groups of detected peptaibols differed from each other only by a single or just a few amino acid changes.

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Fourteen strains of Trichoderma spp. were isolated from Algerian desert soils and assessed for their antagonistic activity against Fusarium crown and root rot of wheat. Biocontrol efficiency of Trichoderma spp. was studied by in vitro and in vivo based bioassay against three pathogenic species: F. culmorum, F. graminearum and F. verticillioides. In vitro based bioassay (dual culture) results obtained with all Trichoderma spp. isolates showed significant decrease in colony diameter of Fusarium species compared to the control. The highest percentages of reduction in colony diameter were obtained with T. harzianum Thr.4 causing a growth reduction of 70.68%, 67.05 and 70.57% against F. culmorum, F. graminearum and F. verticillioides, respectively. All Trichoderma spp. isolates were able to overgrow and sporulate above F. culmorum colonies but no overgrowth was observed with F. graminearum and F. verticilliodes. The seed treatment by Trichoderma spp. isolates before sowing in a soil already infested by the pathogens led to a significant decrease of disease severity compared to the untreated control. The highest disease index decrease (>70%) was obtained with two isolates of T. harzianum (Thr.4 and Thr.10) and T. viride Tv.6 against the three fungal pathogens. Lytic enzymes production by Trichoderma spp. isolates was tested in liquid cultures containing fungal cell walls of each pathogen as sole carbon source. Higher levels of protease and chitinase activities were induced by hyphal cell walls of F. graminearum than cell walls of F. verticillioides and F. culmorum. T. harzianum Thr.4 exhibited the highest enzyme activities with hyphal cell walls of F. graminearum and F. culmorum. However, in the medium amended with cell wall of F. verticillioides, maximal lytic activities were recorded for T. viride Tv.6.

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The leaf blight disease caused by Lasiodiplodia theobromae is an important foliar disease in coconut that results in a yield reduction of 10–24 per cent in Tamil Nadu, India. In the present study, five Trichoderma viride isolates, Pseudomonas fluorescens and Bacillus subtilis strains were isolated from the coconut rhizosphere and tested against L. theobromae. P. fluorescens Pf1, B. subtilis (Km1) and T. viride (TNAU) isolates were found highly effective against the leaf blight pathogen under in vitro conditions and hence, all the three antagonists were combined together to develop microbial consortia and tested against leaf blight disease under field conditions. Soil application of microbial consortia formulated using talc as a carrier material at 150 g (50 g each) and 300 g (100 g each) doses at different intervals (quarterly, half-yearly and annually) was evaluated for three years from 2011 to 2013. Among the treatments, the fungicide carbendazim was found to be the most effective against coconut leaf blight. Among the treatments with bioagents, soil application of microbial consortia @ 300 g+5 kg of farm yard manure at quarterly interval/palm/year was the best treatment which was followed by the treatment with TNAU Bacillus subtilis (Bs1) mixture in two locations. Confirmatory results were obtained in similar experiments carried out at two different locations during 2013–2014, too.

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Seed extracts of 50 plant species belonging to different families were evaluated for their ability to inhibit growth of Trichoderma viride in vitro. Of the various seed extracts, the seed extracts of Harpullia cupanioides (Roxb) belonging to Sapindaceae family exhibited very high antifungal activity. The seed extract of H. cupanioides strongly inhibited the growth of Rhizoctonia solani, Curvularia lunata, Colletotrichum musae and Alter­naria alternata. Seed extract of H. cupanioides retained its antifungal acti­vity even after heating at 100 °C for 10 min or autoclaving at 121 °C for 20 min. For partial purification of antifungal proteins, H. cupanioides seed extract was subjected to ammonium sulphate fractionation followed by gel filtration on Sephadex G-200 column. The fractions from sephadex G-200 were individually tested for their antifungal activity against T. viride. SDS-PAGE analysis of the fractions from Sephadex-G200 column indi­cat­ed that the fractions with antifungal activity contained a 68-kDa band as well as other low molecular weight protein bands. The N-terminal amino acid sequence of the 68-kDa protein (13 residues) was determined by Edman degradation. However, comparison with sequences in the GenBank database (Swiss Prot) did not reveal any homology with known protein sequences.

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Ascochyta blight (Ascochyta rabiei) is one of the most devastating diseases of chickpea. The biocontrol potential of fungal antagonists, Chaetomium globosum, Trichoderma viride, Acremonium implicatum were explored under in vitro and in vivo. A. implicatum isolate-1 overgrew the host mycelium and caused lysis, while A. implicatum isolate-2 produced inhibition zone. C. globosum profusely overgrew the mycelium of A. rabiei and T. viride showed overgrowth and profuse sporulation. Bioassay with culture filtrates of all the antagonists resulted in significant inhibition of pycnidiospore germination and reduction in colony development of A. rabiei. Syringe filtered culture filtrate when amended in liquid broth medium also significantly reduced the mycelial growth. Bioassay of culture filtrates under glass house conditions, although brought reduction in disease development in both pre- and post-inoculation sprays, but C. globosum was the most effective antagonist causing 73.12% reduction in disease index when used as post inoculation spray. Under in vitro conditions C. globosum caused 48.59% reduction in colony diameter and 70.86% reduction in pycnidiospore germination.

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